Here in the States, we had the Ring-necked Turtle Doves for years. These are smaller the the Eurasians and were the bird most commonly released at weddings etc.
I heard two explaination for the new comers (Eurasian Dove). One that they escaped in Florida and spread up and along the coast. The other explanation was that they are the bird of choice for the Vietnamese to release during events.
http://whatbird.com/forums/photos/birdman/